AT&T is accepting pre-orders for the Galaxy S4 starting at $199.99 with a two-year contract. It has not said when the phone will go on sale.

Sprint will sell the Galaxy S4 on April 27 starting at $249.99 with a two-year contract.

US Cellular will also sell the Galaxy S4, but hasn't announced a price or launch date yet.

What's the hold up?

Carriers have to test the Galaxy S4's software to make sure it runs well on their networks before it can start selling the phone. Most carriers also use the testing period to load Android phones like the Galaxy S4 with extra apps and services specific to the carrier. That all takes time.